Heavy duty laundry detergent compositions have for many years contained an anionic sulphonate or sulphate surfactant, for example, linear alkylbenzene sulphonate (LAS) or primary alcohol sulphate (PAS), as the principal detergent-active ingredient. These anionic surfactants are frequently used in conjunction with ethoxylated alcohol nonionic surfactants which give improved detergency on hydrophobic soils.
These anionic and anionic/nonionic surfactant systems are robust and highly efficient on a wide range of soils and under a wide range of conditions, for example, temperature and water hardness. However, the anionic surfactants are not noted for mildness to skin. These materials are designed to interact with fatty materials like body soil and protein residues on soiled laundry, and can therefore interact with the skin to give reactions such as dryness and erythema (redness). The milder surfactants used to formulate products intended for prolonged skin contact, for example, shampoos and shower gels, would not perform adequately in heavy duty laundry detergent compositions because of insufficient interaction with fatty materials occurring as soil.
It is possible substantially to increase the mildness to skin of a laundry detergent composition containing an anionic sulphonate or sulphate detergent and a conventional detergent ethoxylated nonionic surfactant, without detriment to detergency performance, for example, by increasing the proportion of nonionic surfactant in the system, or by incorporating low levels of certain cosurfactants.
While real mildness benefits can be achieved by these means, it is not easy to communicate the concept to the consumer. It has been proposed that the message can be reinforced by the incorporation of aloe vera, an ingredient strongly associated in the mind of the consumer with skin benefits, desirably in a form which also provides a visual cue. Other herbal extracts known for their skin mildness benefits may also be used together with, or instead of, aloe vera.